The Island of Oahu,
Hawaii, provides many opportunities to see the inside of a basaltic shield
volcano because of the considerable degree of erosion of the Koolau
Volcano. Here at a road-cut we see numerous volcanic dikes 0.5–1.0
meters wide that formed along the main rift zone of the Koolau Volcano.
Similar dikes are almost certainly present within the rift zones of Kilauea
and Mauna Loa Volcanos, and act as pathways for the magma as it moves
from the magma chamber to the surface.